From WagaWiki

mojibake 文字化け (もじばけ)

This is the term used for text that appears as gibberish - a series of random meaningless characters. Often refering to text that has been improperly encoded or is displayed with the wrong encoding.

Here is a sample of what 文字化け typically looks like: ŽŸ‚ÉA–œ—t‰¼–¼‚Ìˆê——•\‚ðÚ‚¹‚Ä‚¨‚«‚Ü‚·B

Etymology 語源

The word mojibake 文字化け is derived from the words 文字 moji meaning characters and the noun form of the verb 化ける bakeru meaning to change into another form/appearance. Originally used in the printing business with the latter half of the word in Katakana 文字バケ now that computers have come into common use it has settled into the word seen now 文字化け.

Example of use

「さっき送ってもらったメール、文字化けしてて読めないから、もう一度、ISO-2022-JPで送ってくれない?」
"sakki okutte moratta me-ru, mojibake shitete yomenai kara, mou ichido ISO-2022-JP de okuttekurenai?"
"The email you just sent me was turned into mojibake and couldn't be read so could you send it once more in ISO-2022-Jp?"